[unreadable] Toxicogenomics has emerged as a radical alternative to the slow, expensive and inefficient conventional toxicological approaches. The toxicogenomic approach is based on the premise that exposure to toxic agents elicits unique patterns of gene expression that can be assessed by using gene array technology. However, analyzing expression patterns of tens of thousands genes has been proven challenging. Gene expression is largely regulated on the transcriptional level and is controlled by transcription factors (TFs), proteins that bind regulatory gene elements (promoters and enhancers). An estimated few hundred of distinct TFs families exist that control the expression of approximately 35,000 genes encoded by the human genome. As the complexity of cell regulation is dramatically reduced at the TF level, analyzing the molecular changes occurring at the TF level would provide a much simpler and more comprehensive interpretation of biological effects of tested compounds. ATTAGENE Inc. has developed a multi-transcription factor system (MTFS) suitable for profiling the activities of multiple TFs. The feasibility of this technology has been demonstrated in our preliminary studies. Here, we will utilize the MTFS technology to develop recombinant cell lines that will serve as biosensors for a variety of toxicological applications. A unique feature of the MTFS-based test systems is a modular design that affords assembling many MTFS for assessment of any combination of TFs. Furthermore, the modular design allows for a simple and rapid upgrade of existing MTFSs. In the Phase I research, we will establish the methodology of the MTFS-based biosensors by constructing a prototypical test system suitable for determination of several key TFs controlling the responses to xenobiotics, toxicants, and stress (e.g. PXR, PPARa, AhR, p53, and NF-kB). We will test the utility of this system for profiling the toxicities of a few well-characterized toxicants. Finally, we will assess a long-term performance of the MTFS-based biosensors. In the Phase II research, we will advance our technology to the point where the novel biosensors can be made available for toxicologists. By allowing analyzing practically unlimited numbers of TFs, the MTFS technology expands the toxicogenomic approach to the new level and thus provides a unique tool for toxicological studies. [unreadable] [unreadable] [unreadable]